Hello smart masses

I have an Excel question I'm hoping someone can help me with. I have not as yet googled it, because I haven't the faintest idea how to phrase it so that Google understands what I'm talking about.

Here's my problem.

There is a spreadsheet in Excel (Office 2010 I believe, Mac version) being used to work out salaries for a place I work at. The problem we're finding is that the spreadsheet is giving a total of $xxx.74, but when we add the numbers by hand (well, using a calculator), it comes out as $xxx.75. I know it's just one cent and that may not seem like an issue, but it's actually driving us crazy and is causing problems down the road when it comes to actually paying said salaries through the bank.

The spreadsheet is set up with the hours worked x pay rate, for each employee, then those are totalled into one grand total. All the cells are set to round to 2 decimal places, but in doing some number crunching, we've found that some totals are actually coming to 3dp. By which I mean, that when we've done the hours worked x pay rate on a calculator, some of the totals are coming to 3dp instead of the 2dp that Excel is showing.

My theory is that while Excel is showing only 2dp, when it's adding up the grand total it's adding all 3 decimal places. Does anyone know how to tell Excel to show 2dp and only add those 2dp as well (with appropriate rounding active of course)?

Is this making sense? Do you need more detail? And if all else fails, does anyone have any idea how I could phrase this as a google search to try and find some answers? If nothing else, can anyone tell me what's actually happening here? If I know what's going on, I can probably figure out a way to make it work the way I want it to.

Thanking you in advance